Mammalian twinfilin sequesters ADP-G-actin and caps filament barbed ends: implications in motility - Archive ouverte HAL Access content directly
Journal Articles EMBO Journal Year : 2006

Mammalian twinfilin sequesters ADP-G-actin and caps filament barbed ends: implications in motility

Abstract

Twinfilins are conserved actin-binding proteins composed of two actin depolymerizing factor homology (ADF-H) domains. Twinfilins are involved in diverse morphological and motile processes, but their mechanism of action has not been elucidated. Here, we show that mammalian twinfilin both sequesters ADP-G-actin and caps filament barbed ends with preferential affinity for ADP-bound ends. Twinfilin replaces capping protein and promotes motility of N-WASP functionalized beads in a biomimetic motility assay, indicating that the capping activity supports twinfi-lin's function in motility. Consistently, in vivo twinfilin localizes to actin tails of propelling endosomes. The ADP-actin-sequestering activity cooperates with the filament capping activity of twinfilin to finely regulate motility due to processive filament assembly catalyzed by formin-func-tionalized beads. The isolated ADF-H domains do not cap barbed ends nor promote motility, but sequester ADP-actin, the C-terminal domain showing the highest affinity. A structural model for binding of twinfilin to barbed ends is proposed based on the similar foldings of twinfilin ADF-H domains and gelsolin segments.

Domains

Biophysics
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Dates and versions

hal-01960873 , version 1 (08-02-2019)

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Emmanuèle Helfer, Elisa M. Nevalainen, Perttu Naumanen, Stéphane Romero, Dominique Didry, et al.. Mammalian twinfilin sequesters ADP-G-actin and caps filament barbed ends: implications in motility. EMBO Journal, 2006, 25 (6), pp.1184-1195. ⟨10.1038/sj.emboj.7601019⟩. ⟨hal-01960873⟩
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